It requires 49 J of work to stretch an ideal very light spring from a length of 1.4 m to a length of 2.9 m. What is the value of the spring constant of this spring?

Which would not reduce the amount of green house gasses in the air

Ababy stroller is a rest on top of a hill which is 10 m high. the stroller and baby have a mass of 20 kg. what is the potential energy of the baby and stroller?

Starting with only the balmer series light (visible light), how could we ensure that the solar panels generate a current that mark can use for his power station? a)by gradually increasing the brightness (amount) of light that we shine on it. b)by gradually increasing the frequency of the light we shine on it. c)by gradually increasing the wavelength of the light that we shine on it.